The present invention relates to a laminar structure comprising an organic material and an inorganic material, or a multi-level structure consisted of organic and inorganic compounds. For example, the present invention relates to the structure of a coating on an organic substrate made of an organic material on which an inorganic film must be formed and a method of production thereof, a structure which is suitable for increasing the reliability of an optical disk and a method of production thereof, the structure of wiring on an organic substrate made of an organic material on which electrical wiring must be formed and a method of production thereof, and a structure which is suitable for increasing the reliability of a semiconductor integrated circuit device and a method of production thereof.
When an inorganic film is formed on an organic material, separation or cracks generally occur immediately after the films have been formed because the difference between the coefficients of linear expansion of the two materials is typically about one order of magnitude or more. Means for solving such a problem are the following methods:
A means is disclosed in Japanese Patent Unexamined Publication No. 38746/1985 in which the stress produced owing to the difference between the coefficients of linear expansion of two materials is relieved by inserting a material with a coefficient of linear expansion that is at an intermediate value between those of the first two materials.
Japanese Patent Unexamined Publication No. 109247/1987 disclose in which a nitride film or an oxide film is formed on a plastic substrate while a negative bias voltage is applied thereto by a sputtering apparatus using a sintered metal substance which is subjected to the ion impact of an inert gas, and in which a recording film is then formed thereon.
On the other hand, Japanese Patent Unexamined Publication No. 120642/1987 discloses a method in which an Si.sub.3 N.sub.4 film is formed separately on an insulating film and recording film by decomposition of a monosilane (SiH.sub.4) gas with N.sub.2 plasma using electron cyclotron resonance plasma.
In each of the above-described methods, the film formed between the substrate and the recording film is an inorganic film composed of a metal compound such as SiO or Si.sub.3 N.sub.4.
However, it was found that separation or cracks occur in the metal compound films after the passage of a relatively short time (for example, 100 to 200 hours) in high-temperature high-humidity tests (for example, 60.degree. C. and 95% RH), and thus the structures formed by the above-described prior art exhibit low degrees of strength, durability or reliability.
In the structure of multilayer interconnection in LSI elements or the like, an organic material such as polyimide resin is sometimes used in an interlayer film. In this case, the reaction of the organic material with an inorganic material such as a metal wiring material in some cases causes metal ions to enter the organic material which is thus degraded, depending upon the type of inorganic material used.
As a method of removing the above-described problem, a method is considered in which a thin film which does not react with either an inorganic material such as a wiring material or an organic material is interposed between these materials.
In addition, when an inorganic material such as a metal wiring film is formed on an organic material, since the coefficients of linear expansion of the two materials greatly differ from each other, and since the organic material is not easily bound with the inorganic film in a direct manner, a low adhesive force between these materials causes separations or cracks immediately after the film has been formed. As a means for solving this problem, a sintered metal substance is generally formed in a plasma by a sputtering apparatus using the ion impact of an inert gas.
As described above, films respectively formed between organic substrates and wiring materials are inorganic films composed of a metal compound such as SiO or Si.sub.3 N.sub.4.
However, it was found that the substrate formed by the above-described prior art produces separation in the metal compound film at 50 g/cm in a tension test and thus exhibits a low degree of strength, durability or reliability.